Development of nonlinear elastic bending and torsion of articulated rotor blades with an impedance control device replacing the common pitch link

Publication

Publication

Presented at the
31st European Rotorcraft Forum (September 2005), Florence

In this paper, the time-dependent non-linear partial differential equations of motion for both cantilever and articulated rotorcraft blades are derived based on a Newtonian approach. In the former case, the initial-boundary value problem is solved using linearized equations, via a central finite difference method. Deflection, bending moment, and shear force distributions during the vibration have been obtained. Included in the latter case is a semi-active impedance control device that attenuates higher-harmonic vibration transmitted from the blade to the rotorcraft frame. This device reduces the transmissibility ratio by replacing the pitch link and controlling the boundary conditions at the root of the blade. Based on the system state, the controller device engages or disengages the piezoelectric actuators that change the effective mass and stiffness. In this way, the elastodynamic system is complicated further by time-variant boundary conditions. Further research is currently in progress in order to evaluate the effect of the proposed control system on reducing the blade-frame transmissibility ratio.